Audio signal recording medium and recording and reproducing apparatus for recording medium

ABSTRACT

A recording medium for a disc etc. according to the present invention comprises at least a first recording region in which a first portion of audio signals supplied is recorded and a second recording region in which a second portion of audio signals supplied is recorded. The first and second portions of the audio signals recorded in the first and second recording regions are synthesized and reproduced or selected and reproduced to realize variegated audio reproduction.

TECHNICAL FIELD

[0001] This invention relates to a recording medium, a recordingapparatus for the recording medium, a reproducing apparatus for therecording medium, a recording method for audio signals and a reproducingmethod for audio signals. More particularly, it relates to a recordingmedium on which to record audio signals, a recording apparatus for therecording medium, a reproducing apparatus for the recording medium, arecording method for audio signals and to a reproducing method for audiosignals.

BACKGROUND ART

[0002] On a compact disc, referred to below simply as CD, which is astandardized optical disc with a diameter of 12 cm, there are recordedaudio signals, as digital data converted from analog audio signals.

[0003] On a routine CD, there is recorded a musical number as a set ofaudio data making up the musical number. For example, if a musicalnumber is made up of a lyric and the accompaniment music for this lyric,the lyric and the accompaniment music are recorded as one as a set ofaudio data.

[0004] In an orchestra performed by plural sorts of musical instruments,the performance by the plural sorts of musical instruments is recordedas one as a set of audio data.

[0005] In a disc on which the lyric and the accompaniment music thereforhave been recorded as one as a set of audio data, it is not possible toselect and reproduce only the lyric or the accompaniment music, suchthat, when only the accompaniment music of a musical number is to bereproduced, the accompaniment music needs to be recorded independentlyof audio data containing the lyric and the accompaniment music.

[0006] Even in case of a disc having recorded thereon as one theperformance by the plural sorts of musical instruments as a set of audiodata, it is not possible to reproduce the performance by only a certainmusical instrument forming an orchestra, such as a piano.

DISCLOSURE OF THE INVENTION

[0007] It is therefore an object-of the present invention to provide arecording medium whereby it is possible not only to reproduce a musicalnumber made up of a lyric and the accompaniment music or the orchestraperformed by plural sorts of musical instruments as a set of audiosignals, but also to reproduce only the accompaniment music of a musicalnumber made up of the lyric and the accompaniment music or only theperformance by certain musical instrument(s) of the orchestra.

[0008] It is another object of the present invention to provide arecording method and apparatus whereby it is possible to record readilythe audio signals recorded on a recording medium which enables recordingof a set of audio signals in their entirety or only a portion of thelyric or the accompaniment music of the set of audio signals.

[0009] It is yet another object of the present invention to provide areproducing method and apparatus whereby it is possible to select andreproduce readily the audio signals recorded on a recording medium whichenables recording of a set of audio signals in their entirety or only aportion of the lyric or the accompaniment music of the set of audiosignals.

[0010] A recording medium proposed for accomplishing the above objects,according to the present invention, at least includes a first recordingregion for recording a first portion of supplied audio signals, and asecond recording region for recording a second portion of supplied audiosignals. The first and second portions of the audio signals, recorded onthe first and second recording regions, respectively, are synthesizedand reproduced or selected and reproduced.

[0011] The recording medium according to the present invention includesn recording regions in which sampled data generated on sampling audiosignals from a sound source with a sampling frequency of 44.1 kHz arerecorded from one of n partial portions to another, with each partialportion being recorded in each recording region.

[0012] According to the present invention, in reproducing audio signalsfrom a recording medium on which audio signals from a sound source aresampled by a pre-set sampling frequency to generate sampled data whichsampled data are separated into n partial portions, at least one ofwhich is the entire sampled data, signals are read out from the nrecording regions of the recording medium, and the read-out signals ofthe respective recording regions of the n recording regions of therecording medium are selectively reproduced. Alternatively, the datarecorded in at least two of the entire recording regions are synthesizedand reproduced.

[0013] Moreover, according to the present invention, in reproducing arecording medium having a first recording region in which a firstportion of audio signals supplied is recorded and a second recordingregion in which a second portion of audio signals supplied is recorded,there being recorded on the recording medium a discrimination signalindicating whether the first and second portions are to be output onaddition or on substation, the first portion read out from the firstrecording region and the second portion read out from the secondrecording region is reproduced based on the contents of thediscrimination signal read out from the recording medium.

[0014] Other objects, features and advantages of the present inventionwill become more apparent from the following detailed description of thepresent invention and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a cross-sectional view showing an embodiment of anoptical disc embodying the present invention.

[0016]FIG. 2 illustrates two optical pickups adapted for recording audiosignals on first and second recording layers of an optical disc.

[0017]FIG. 3 is a block diagram showing an embodiment of a recordingapparatus and an embodiment of a reproducing apparatus according to thepresent invention.

[0018]FIG. 4 is a cross-sectional view showing the state of recordingaudio signals on first and second recording layers of an optical discaccording to the present invention and the state of reproducing therecorded audio signals.

[0019]FIG. 5 is a block diagram showing a modification of a reproducingapparatus according to the present invention.

[0020]FIGS. 6A to FIG. 6C show switching timing in reproducing the audiosignals recorded on plural recording layers on the optical disc by areproducing apparatus shown in FIG. 5.

[0021]FIG. 7 is a block diagram showing a modification of a recordingapparatus according to the present invention.

[0022]FIG. 8 shows a modification of an optical disc according to thepresent invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0023] Referring to the drawings, a recording medium, a recordingapparatus and a reproducing apparatus according to the present inventionwill be explained in detail.

[0024] A recording medium according to the present invention iscomprised of an optical disc 1, which is provided with a substrate 2 ofa light-transmitting synthetic resin, such as polycarbonate resin, orglass, as shown in FIG. 1. On one surface of the substrate 2, there isprovided a pit pattern 3 which is a pattern of micro-sized crests andgrooves corresponding to recorded audio data. If the substrate 2 ismolded from synthetic resin, this pit pattern 3 is formed simultaneouslywith the molding of the substrate 2 by a stamper mounted on an injectionmolding system in injection molding the substrate 2. If the substrate 2is formed of glass, it is molded using a 2P (PhotoPolymerization)method. In this 2P method, a photo-curable resin, such as UV lightcurable resin, is charged between a glass substrate and a stamper, andthe light, such as UV light is illuminated from the side glass substrateto cure the pattern of the crests and grooves of the stamper in order totranscribe the pattern of the crests and grooves of the stamper to thelayer of the photo-curable resin.

[0025] The substrate 2, used in this optical disc 1, is obtained oninjection molding a polycarbonate resin. On one surface of the substrate2 is formed audio data as pit pattern 3. Similarly to the substrate ofthe so-called routine Compact Disc (CD), the substrate 2 is of adiameter of 12 cm and a thickness of approximately 1.2 mm.

[0026] On one surface of the substrate 2, carrying the pit pattern 3,there is formed a first recording layer 4 for overlying the pit pattern3, as shown in FIG. 1. This first recording layer 4 is formed as asemi-transparent film for transmitting a pre-set portion of a light beamradiated from the side substrate and for reflecting a pre-set portionthereof, and is formed as a film of silicon-based material, such asSi₃N₄ and SiO₂ to a thickness of 100 to 500 nm. The first recordinglayer 4 is formed as a multi-layer of Si₃N₄ and SiO₂. The layers ofSi₃N₄ and SiO₂, making up the first recording layer 4, are formed on onesurface of the substrate 2 by vacuum deposition or sputtering.

[0027] On the first recording layer 4 is formed a second recording layer6 via an intermediate layer 5 formed e.g., of a light-transmitting UVlight curable resin. The intermediate layer 5 is formed to a pre-setthickness because the intermediate layer 5 performs the role ofoptically separating the first recording layer 4 and the secondrecording layer 6 from each other so that these recording layers 4, 6will not be positioned within the depth of focus of an objective lenswhich is adapted for converging the light beam to these recording layers4, 6 to illuminate the recording layers. Specifically, the intermediatelayer 5 is formed to a thickness on the order of 30 μm. The intermediatelayer 5, if too thin in thickness, is unable to separate the reflectedlight from the first recording layer 4 sufficiently from the reflectedlight from the recording layer 6, to render it difficult to detect thereflected light beams sufficiently. If conversely the intermediate layer5 is too thin, spherical aberration, for example, is produced by theintermediate layer 5. Accordingly, the intermediate layer 5 is set to anappropriate thickness taking these points into consideration.

[0028] It is noted that the intermediate layer 5 is formed by coating aUV light curable resin on the first recording layer 4 by a spin coatingmethod and subsequently illuminating the UV light for curing.Alternatively, the intermediate layer 5 may be formed on depositing theUV light curable resin layers, each being of a thickness of 5 to 10 μm,a plurality of numbers of times. Still alternatively, the intermediatelayer 5 may be formed by bonding a transparent sheet on the firstrecording layer 4.

[0029] On one surface of the intermediate layer 5 is formed a pitpattern 7, which is a pattern of micro-sized crests and groovescorresponding to audio data. This pit pattern 7 may also be formed bythe above-mentioned 2P method which is used in forming a pit pattern ona glass substrate using the photo-curable resin, as described above.

[0030] The second recording layer 6 is formed to overlie the pit pattern7 formed on one surface of the intermediate layer 5 in superposition onthe first recording layer 4. The second recording layer 6 is formed of amaterial exhibiting high reflectance, such as aluminum (Al), gold (Au)or silver (Ag) on the intermediate layer 5 with the pit pattern 7, inorder to reflect the light beam transmitted through the first recordinglayer 4 and radiated therefrom with high efficiency onto an opticalpickup mounted facing the substrate 2 to output a light beam. On thesecond recording layer 6 is formed a protective layer 8 formed e.g., ofa UV light curable resin to protect the second recording layer 6. Thisprotective layer 8 is formed by coating a UV light curable resin on thesecond recording layer 6 by a spin coating method and illuminating theUV light thereon to cure the UV light curable resin.

[0031] On this first recording layer 4, there are recorded audio datacorresponding to the accompaniment music separated from a completemusical number composed of the lyric and the accompaniment music of thislyric, as partial audio data, whereas, on the second recording layer 6,there are recorded audio data corresponding to the entire completemusical number composed of the lyric and the accompaniment music of thislyric.

[0032] The audio data may be recorded in various configurations on thefirst and second recording layers 4, 6. For example, the audio datacorresponding to the accompaniment music separated from the completemusical number composed of the lyric and the accompaniment music may berecorded as partial audio data on the first recording layer 4, with theaudio data corresponding to the lyric being also recorded on the secondrecording layer 6 as partial audio data.

[0033] In the case of a musical number, such as orchestra performed byplural sorts of musical instruments, audio data portions correspondingto the audio data performed by a piano of the orchestra may be recordedas partial audio data. On the other hand, the first recording layer 4,with the entire audio data comprised of the complete orchestra, beingthen recorded on the second recording layer 6 as partial audio data.

[0034] The respective audio data, recorded as respective partial audiodata portions of the complete musical number, on the first and secondrecording layers 4, 6, are recorded as lyric or its accompaniment music,the audio data as self-contained pieces of the musical number, eachforming a musical number set, so that, even if only one of the first andsecond recording layers 4, 6 is reproduced, self-contained audio data,as a portion of the musical number, is reproduced.

[0035] The audio data, recorded on the first and second recording layers4, 6, are generated by sampling at a sampling frequency of 44.1 kHzfollowed by 16-bit quantization of analog audio signals supplied from asignal source for recording on the respective recording layers.

[0036] The audio data, recorded on the first and second recording layers4, 6, are recorded thereon to be reproduced by a disc reproducing deviceemploying an light beam having a wavelength of approximately 780 nm.

[0037] On one or both of the first and second recording layers 4, 6 ofthe optical disc 1 are recorded discrimination data for discriminatingthe combination of the partial audio data recorded on the first and/orsecond recording layers 4, 6. If audio data corresponding to theaccompaniment music, separated from the complete musical number composedof the lyric and the accompaniment music for this lyric, is recorded aspartial audio data, the discrimination data is data indicating theaddition of the partial audio data recorded on the first and secondrecording layers 4, 6, whereas, if the entire music composed of thelyric and the accompaniment music for this lyric is recorded on thefirst recording layer 4 as partial audio data and the audio datacorresponding to the lyric is recorded as partial audio data, thediscrimination data is data indicating the subtraction the partial audiodata recorded on the second recording layer 6 from the partial audiodata recorded on the first recording layer 4. This discrimination datais recorded on e.g., a recording area, carrying e.g., management orarchival data, of one of the first and second recording layers 4, 6which is read out first next to the loading of the optical disc 1 on thereproducing apparatus.

[0038] A recording apparatus for recording audio data on the opticaldisc 1, on which there are recorded different portions separated from acomplete musical number, as respective audio data portions, or audiodata corresponding to the entire musical number and a potion of themusical number, as respective audio data portions, and a reproducingapparatus for reproducing the optical disc recorded by this recordingapparatus, are hereinafter explained.

[0039] First, a recording apparatus 12 for recording audio data on theoptical disc 1, according to the present invention, is explained.

[0040] Referring to FIG. 2, the recording apparatus 12 of the presentinvention includes two optical pickups, having a first objective lens 9and a second objective lens 10. A recording light beam L₁, converged bythe first objective lens 9, is focussed on the first recording layer,and a recording light beam L₂, converged by the second objective lens10, is focussed on the second recording layer 6 for recording audio dataon the first and second recording layers 4, 6.

[0041] Referring to FIG. 3, the recording apparatus 12 according to thepresent invention includes a first input terminal 13, fed with audiosignals, recorded on the first recording layer 4, and a second inputterminal 113, fed with audio signals recorded on the second recordinglayer 6.

[0042] In the complete musical number composed of the lyric and theaccompaniment music for this lyric, signals for the accompaniment musicare separated and audio signals corresponding to this accompanimentmusic are fed as partial audio data to the first input terminal 13. Onthe other hand, signals corresponding to the lyric of the musical numberare separated so that audio signals corresponding to this lyric are fedto the second input terminal 113. That is, in the recording apparatus 12according to the present invention, the signals corresponding to thelyric and the signals corresponding to the accompaniment music areseparated from the complete musical number, made up of the lyric and theaccompaniment music, from a reproducing apparatus, not shown, operatingas a sound source for reproducing e.g., a master tape having recordedthereon the original sound. The audio signals of the lyric and those ofthe accompaniment music, thus separated, are fed to the first and secondinput terminals 13, 113, respectively. Alternatively, the audio signalsproduced on reproducing a master tape, having separately orindependently recorded thereon the lyric and the accompaniment music,making up a complete musical number, are input to the first and secondinput terminals 13, 113, respectively.

[0043] Meanwhile, the audio signals input to the first and second inputterminals 13, 113 are left channel audio data and right channel audiodata in order to permit stereophonic reproduction.

[0044] The analog audio data, input to the first and second inputterminals 13, 113, and which correspond to the lyric portion and to theaccompaniment music portion, respectively, are routed to first andsecond A/D converters 14, 114 where the signals are sampled at thesampling frequency of 44.1 kHz accepted by these A/D converters 14, 114,and quantized in 16 bit stereophonic two-channel audio signals, to beoutput from the A/D converters 14, 114.

[0045] The digital audio signals, output from the first D/A converter14, are sequentially routed to a first error correction coding circuit16, a first modulation circuit 17 and a first bi-level circuit 18,making up a signal processing system responsible for recording on thefirst recording layer 4.

[0046] Similarly, the digital audio signals, output from the A/Dconverter 114, are sequentially routed to a second error correctioncoding circuit 116, a second modulation circuit 117 and a secondbi-level circuit 118, makingup a signal processing system responsiblefor recording on the second recording layer 6.

[0047] The first and second error correction coding circuits 16, 116encode samples with the combination of the cross-interleaving andfour-order Reed-Solomon code, using an algorithm of the cross interleaveReed-Solomon code (CIRC). The first and second modulation circuits 17,117 modulate encoded outputs of the first and second error correctioncoding circuits 16, 116 in accordance with the algorithm of EFM (eightto fourteen modulation). The first and second bi-level circuits 18, 118convert modulated outputs of the first and second modulation circuits17, 117 into bi-level data for recording on the first and secondrecording layers 4, 6 of the optical disc 1, respectively.

[0048] The data fed from the first input terminal 13 and converted intobi-level data by the above-described signal processing system, that isrecording data output by the bi-level circuit 18, are recorded by thefirst optical pickup having the first objective lens 9 shown in FIG. 2on the first recording layer 4. The recording data fed from the secondinput terminal 113 and converted by the above-described signalprocessing system into bi-level data, that is recording data output bythe bi-level circuit 118, are recorded on the second recording layer 6by the second optical pickup having the second objective lens 10 shownin FIG. 2.

[0049] A reproducing apparatus for reproducing the optical disc 1,having recorded in its first recording layer 4 signals of a lyricportion of a complete musical number composed of the lyric portion andthe accompaniment music for the lyric portion, and also having recordedin its second recording layer 6 signals of the accompaniment musicportion, is now explained.

[0050] Referring to FIG. 2, this reproducing apparatus 20 includes twooptical pickups, one of which has the first objective lens 9 and theother of which has the second objective lens 10. The recording lightbeam, converged by the first objective lens 9, is focussed on the firstrecording layer 4, the recording light beam, converged by the secondobjective lens 10, is focussed on the second recording layer 6 and thereturn light beam reflected from the first and second recording layers4, 6 are detected to reproduce the audio data recorded on the first andsecond recording layers 4, 6. It is of course possible to use a soleoptical pickup and to switch the focussing position of the light beamilluminated from the objective lens on the optical disc 1 from the firstrecording layer 4 to the second recording layer 6 and vice versa.

[0051] In the reproducing apparatus 20, signals read out by the firstoptical pickup from the first recording layer 4 of the optical disc 1rotationally driven at e.g., CLV by a rotational driving unit, notshown, are sequentially routed to a first RF circuit 21, a firstdemodulating circuit 22 and to a second error correction circuit 23,making up a playback signal processing unit. The first RF circuit 21performs RF processing, such as amplification, on the signals read outfrom the first optical pickup, to generate RF signals, which are routedto the first demodulating circuit 22. The first demodulating circuit 22performs EFM demodulation on the RF signals to route the demodulatedsignals to the first error correction circuit 23. The first errorcorrection circuit 23 corrects the demodulated output data from thefirst demodulating circuit 22 by CIRC to route the resulting data to afirst error interpolation circuit 24. The first error interpolationcircuit 24 interpolates the corrected output data from the correctioncircuit 23.

[0052] Similarly to the signals read out by the first optical pickupfrom the first, recording layer 4, the signals read out by the secondoptical pickup from the second recording layer 6 of the optical disc 1are sequentially routed to a second RF circuit 121, a seconddemodulating circuit 122 and to a second error correction circuit 123.The second RF circuit 121 performs RF processing, such as amplification,on the signals read out from the second optical pickup, to generate RFsignals, which are routed to the second demodulating circuit 122. Thesecond demodulating circuit 122 performs EFM demodulation on the RFsignals from the second RF circuit 121 to route the demodulated signalsto the second error correction circuit 123. The second error correctioncircuit 123 corrects the demodulated output data from the demodulatingcircuit 122 by CIRC to route the resulting data to a second errorinterpolation circuit 124. The second error interpolation circuit 124interpolates the corrected output data from the correction circuit 123.

[0053] Meanwhile, the reproducing apparatus 20 includes a playback modeselection button, not shown. This playback mode selection button selectsthe playback mode of audio data recorded on the optical disc 1.

[0054] On output sides of the first and second error interpolationcircuits 24, 124, there are provided first and second data outputselection circuits 25, 125 for selecting the outputting of audio dataread out from the first and second recording layers 4, 6 by selecting aplayback mode selection button, not shown.

[0055] If a playback mode selection button, not shown, is acted on by auser, and a playback mode according to-the discrimination datapre-recorded on the optical disc 1, the audio data read out from thefirst and second recording layers 4, 6 are routed to the multiplexer 26through the first and second data output selection circuits 25, 125. Themultiplexer 26, fed with the audio data read out from the first andsecond recording layers 4, 6, sums or subtracts the audio data read outfrom the first recording layer 4 and the audio data read out from thesecond recording layer 6 to output the resulting data.

[0056] For example, if, when audio data corresponding to accompanimentmusic, separated from the complete musical number comprised of a lyricand the accompaniment music for this lyric, is recorded on the firstrecording layer 4, as partial audio data, and audio data correspondingto the lyric is recorded as partial audio data in the second recordinglayer 6, discrimination data is recorded as data indicating summation ofaudio data read out from the first and second recording layers 4, 6, themultiplexer 26 sums the audio data read out from the first and secondrecording layers 4, 6 to output the summation data this summation datais audio data of the complete musical number containing audio datacorresponding to the accompaniment music recorded on the first recordinglayer 4 and also containing audio data corresponding to the lyricrecorded on the second recording layer 6.

[0057] If, when audio data corresponding to the entire complete musicalnumber comprised of a lyric and the accompaniment music for this lyric,is recorded on the first recording layer 4, as partial audio data, andaudio data corresponding to the lyric is recorded as partial audio datain the second recording layer 6, discrimination data is recorded as dataindicating subtraction of the partial audio data recorded on the secondrecording layer 6 from the audio data read out from the first recordinglayer 4, the multiplexer 26 subtracts the audio data read out from thesecond recording layer 6 from the audio data read out from the firstrecording layer 4 to output the resulting subtraction data. Thissummation data is audio data containing only audio data corresponding tothe accompaniment music of the lyric.

[0058] The audio data, summed or subtracted by the multiplexer 26, isrouted to a first low-pass filter (LPF) 27. The first LPF 27 appliesfiltering to audio data output from a multiplexer 26 with approximately20 kHz as a cut-off frequency. The audio data, filtered by the first LPF27, is routed to a first D/A converter 28 for conversion to analog audiosignals which are output from the first output terminal 29. Byconnecting a reproducing apparatus having an electro-acoustictransducer, such as a loudspeaker or a headphone, to the first outputterminal 29, there is produced acoustic reproduction by the audio soundcorresponding to the sum of the audio data read out from the firstrecording layer 4 and audio data read out from the second recordinglayer 6, or acoustic reproduction by the audio sound corresponding tothe audio data read out from the first recording layer 4 less the audiodata read out from the second recording layer 6.

[0059] If a playback mode selection button, not shown, is acted on bythe user, such that the playback mode for independently outputting audiodata read out from the first and second recording layers 4, 6 of theoptical disc 1 is selected, the audio data read out from the first andsecond recording layers 4, 6 is sent via first and second data outputselection circuits 25, 125 to second and third LPFs 27 a, 27 b. Thesesecond and third LPFs 27 a, 27 b apply filtering, with approximately 20kHz as a cutoff frequency, to the audio data output by the first andsecond data output selection circuits 25, 125. The audio data, filteredby the second and third LPFs 27 a, 27 b, are routed to second and thirdD/A converters 28 a, 28 b, for conversion into analog audio signals,which are output from second and third output terminals 29 a, 29 b,respectively. By connecting a reproducing apparatus, such as aloudspeaker or a headphone, provided with an electro-acoustictransducer, acoustic reproduction takes place by the audio sound basedon audio data read out from the first and second recording layers 4, 6.By selecting signals output by the second and third output terminals 29a, 29 b, audio data recorded on the first and second recording layers 4,6 can be selectively reproduced and heard by the user.

[0060] By recording plural partial audio data of the complete musicalnumber, or a partial audio data and the entire audio data, in the firstand second recording layers 4, 6 provided on the optical disc 1, and bysumming or subtracting the audio data read out from the recording layers4, 6, it is possible to realize diversified acoustic reproduction.

[0061] It is noted that, since the audio data are recorded on the firstand second recording layers 4, 6 of the optical disc 1 as meaningfulaudio data from one partial audio data recorded on the recording layer 4or 6 to another, acoustic reproduction similar to that realizedconventionally can be achieved by reproducing audio data recorded onlyon the recording layer 4 or 6 by a reproducing apparatus provided with asole optical pickup having a sole objective lens.

[0062] Referring to FIGS. 4 and 5, another embodiment of a reproducingapparatus for reproducing an optical disc 1, having plural partial audiodata of a complete musical number or the entire musical number andpartial audio data thereof, recorded on the first and second recordinglayers 4, 6, is explained with reference to FIGS. 4 and 5.

[0063] This reproducing apparatus 30 includes a readout mechanism,having an optical pickup 31 and a signal readout unit 32 for reading outaudio data recorded on the first and second recording layers 4, 6 of theoptical disc 1, a first buffer memory 33 for memorizing playback datacorresponding to the audio data recorded on the first recording layer 4and reproduced with modulation and error correction processing by thesignal readout unit 32, and a second buffer memory 34 for memorizingplayback data corresponding to the audio data recorded on the secondrecording layer 6 and reproduced with modulation and error correctionprocessing by the signal readout unit 32. The reproducing apparatus 30also includes a multiplexer 35 for summing or subtracting outputs readout from the first and second buffer memories 33, 34 and a servo circuit38 for causing movement of the objective lens of the optical pickup 31in a direction parallel and/or perpendicular to the optical axis of theobjective lens to control the light beam-radiated from the opticalpickup 1 to scan the target recording track of the optical disc 1. Theservo circuit 38 is also provided with a switching unit 39 for switchingthe light beam radiated from the optical pickup 31 and converged by theobjective lens 11 so that the light beam will be selectively focussed onone of the first and second recording layers 4, 6. The reproducingapparatus 30 also includes a spindle motor 40 for rotationally drivingthe optical disc 1 at a CLV or CAV under control by the servo circuit38.

[0064] The reproducing apparatus 30 includes a CPU (centralprocessing-unit) 37 for deciding whether the audio data recorded on thefirst and second recording layers 4, 6 of the optical disc 1 are to bereproduced, the audio data recorded on the first and second recordinglayers 4, 6 are to be synthesized and reproduced, or a conventionaloptical disc, such as CD, is to be reproduced, under a command from auser or depending on the configuration of the disc to be loaded, and forcontrolling the servo circuit 38, switching unit 39, signal readout unit32 and a buffer management unit 36 depending on the results of decision.To the CPU 37 is connected an operating unit, not shown, provided with aplayback mode selection button for the user to select the playback modeof the optical disc 1.

[0065] Meanwhile, in the present reproducing apparatus 30, the audiodata read out from the first and second recording layers 4, 6 may bestored in different memory storage areas of a common buffer memory 34without employing the two buffer memories, namely the first and secondbuffer memories 33, 34.

[0066] In the reproducing apparatus 30, the audio data read out from thefirst and/or second recording layers 4, 6 of the optical disc 1 arerouted to the signal readout unit 32. Based on control signals from theservo circuit 38 and the switching unit 39, the optical pickup 31 iscontrolled to focus a light beam selectively on the first recordinglayer 4 or on the second recording layer 6 to scan the first or secondrecording layer 4, 6.

[0067] The signal readout unit 32, making up a readout mechanism alongwith the optical pickup 31, performs pre-set RF processing, such asamplification, or replay signal processing, such as demodulation anderror correction processing, on the output signal of the optical pickup31, that is the signal derived from the audio data read out from thefirst or second recording layer 4, 6, to route the processed signal tothe first buffer memory 33 or the second buffer memory 34.

[0068] The first buffer memory 33 is a memory for writing or reproducingreplay data corresponding to audio data recorded on or read out from thefirst recording layer 4 or reproducing the replay data, and the secondbuffer memory 34 is a memory for writing replay data corresponding toaudio data recorded on or read out from the second recording layer 6.Data writing or readout on or from the first buffer memory 33 or thesecond buffer memory 34 is controlled by the buffer management unit 36.

[0069] The operation of the reproducing apparatus 30 shown in FIG. 5 isnow explained in detail.

[0070] If the user acts on the a playback mode selection button, notshown, provided on the reproducing apparatus, and the command is toreproduce only the audio data recorded on the first recording layer 4 ofthe optical disc 1, the CPU 37 selects reproduction of audio data onlyfrom the first recording layer 4, so that the optical pickup 31 iscontrolled by the servo circuit 38 and the switching unit 39 to focusthe light beam on the first recording layer 4 of the optical disc 1, runin rotation by the spindle motor 40, to scan only the first recordinglayer 4 of the optical disc 1. If the optical pickup 31 is controlled toscan the first recording layer 4, the return light beam reflected backonly from the first recording layer 4 is detected by a photo detector ofthe optical pickup 31, so that an output signal of the optical pickup 31is sent to the signal readout unit 32 to read out only audio datarecorded on the first recording layer 4. The output data derived fromthe audio data recorded on the first recording layer 4 and which isoutput by the signal readout unit 32 is subjected to pre-set replayprocessing, such as demodulation and error correction, so as to bewritten in the first buffer memory 33 at a pre-set timing under controlby the buffer management unit 36. The data then is read out from thefirst buffer memory 33 so as to be output from an output terminal 41 viaa multiplexer 35.

[0071] The audio data, read out from the first recording layer 4, isconverted by an error interpolation unit 25, an LPF 26 and a D/Aconverter 27, similar to those used in the respective apparatus 20 shownin FIG. 3, so as to be output at the output terminal 41.

[0072] If a replay mode selection button, not shown, provided on thereproducing apparatus 30, is acted on by the user, such that the replaymode of reproducing only audio data recorded on the second recordinglayer 6 of the optical disc 1 is selected, the processing similar tothat when the replay mode of reproducing only the first recording layer4 occurs to read out the audio data recorded on the second recordinglayer 6. The audio data so read out are converted into analog audiosignals which are output at the output terminal 41.

[0073] If a replay mode selection button, not shown, provided on thereproducing apparatus 30, is acted on by the user, so that the replaymode of multiplexing and reproducing audio data recorded on the firstand second recording layers 4, 6 of the optical disc 1 is selected, theaudio data is reproduced by the following sequence of operations: Thatis, if the replay mode for multiplexing reproduction is selected, theCPU 37 decides to multiplex and reproduce the audio data read out fromthe first and second recording layers 4, 6 of the optical disc 1. If thereplay mode of multiplexing and reproducing the audio data is decided,the optical pickup 31 is switchingly controlled, by the servo circuit 38and the switching unit 39, to focus the replay light beam on one of thefirst and second recording layers 4, 6. The focussing point switchingtiming to the first or second recording layer 4, 6 is selected so that,in reproducing audio data recorded on the second recording layer 6 afterreproducing audio data recorded on the first recording layer 4, thesecond recording layer 6 commences to be reproduced at a time pointprevious to the replay end time point of the audio data of the firstrecording layer 4 on the time axis, and so that reproduction iscontinued up to a time point posterior to the reproduction end timepoint of audio data on the first recording layer 4, with thereproduction being then shifted to a focussed position of the light beamon the first recording layer 4. That is, referring to FIG. 6A, ifreproduction is made from a point P₁₁ on the first recording layer 4 upto a point P₁₂ on the first recording layer 4 and subsequently thereproduction is to be shifted to the second recording layer 6, thefocussing point of the light beam reverts to a point temporally previousto the replay end time point P₁₂ on the first recording layer 4 toinitiate the reproduction of the second recording layer 6 as from thetime point P₂₁, the second recording layer 6 is reproduced as from thereplay end time point P₁₂ on the first recording layer 4 up to atemporally posterior point P₂₂, and reproduction is initiated with thefocussing point of the light beam on the point P₁₂ on the firstrecording layer 4. Reproduction as from the point P₁₂ on the firstrecording layer 4 continues up to a point P₁₃ temporally posterior tothe replay end time point P₂₂ on the second recording layer 6. Ifreproduction is to be transferred to the second recording layer 6, thefocussing point of the light beam is caused to revert to the replay endtime point P₂₂ of the second recording layer 6 so that the secondrecording layer 6 is reproduced up to a time point P₂₃ temporallyposterior to the replay end point P₁₃ of the first recording layer 4.Meanwhile, the focussing point of the light beam is switched by movingthe light beam focussing point along the optical axis of the objectivelens 11 of the optical pickup 31, that is along the focussing direction.

[0074] The audio data read out at the replay timing shown in FIG. 6Afrom the first and second recording layers 4, 6 at the replay timingshown in FIG. 6A are routed to the signal readout unit 32 so as to bereproduced in accordance with the above-mentioned timing as describedabove. In outputting readout signals read out from the first or secondrecording layers 4, 6, the signal readout unit 32 outputs to the CPU 37discrimination data indicating whether the data pre-recorded on thefirst and second recording layers 4, 6 and read out therefrom is to besummed or subtracted. The CPU 37 controls the write or readout timing toor from the first and second buffer memories 33, 34 via buffermanagement unit 36.

[0075] The data write timing to the first or second buffer memories 33,34 is analogous to the replay timing shown in FIG. 6A or readout timingin the signal readout unit 32. On the other hand, data readout timingfrom the first or second buffer memories 33, 34 is set so that datareadout will be initiated after storage of a pre-set quantity of datawritten in the first and second buffer memories 33, 34. Theoretically,data is read out from the optical disc 1 at a high readout speed notless than twice the prescribed standard readout speed and written at theaforementioned timing in the first and second buffer memories 33, 34.The audio data recorded on the first or second recording layers 4, 6 areread out and reproduced. After a pre-set amount of data has been writtenin the first or second buffer memories 33, 34, output data correspondingto the audio data recorded on the second or first recording layers 6, 4is read out from the first buffer memory 33 or from the second buffermemory 34 so as to be multiplexed by the multiplexer 35. Fornon-interrupted reproduction from the first or second recording layer 4,6, at least the double speed is required, as described above, if theswitching time in switching the replay timing of the first and secondrecording layers 4, 6, is also taken into account. In actuality, thespindle motor 40 is run in rotation at a speed not less than thequadrupled speed so that the optical pickup 31 will read out the datarecorded on the optical disc at high read-out rate.

[0076] The changeover timing in illuminating the first or secondrecording layers 4, 6 as the focussing position of the playback lightbeam radiated from the optical pickup 31 is switched between therecording layers 4 and 6 may be such a timing as is shown in FIG. 6B.The first recording layer 4 is reproduced as from the time point P₁₁ upto the time point P₁₂ in the first recording layer 4. When reproductionis to be shifted to the second recording layer 6, the second recordinglayer 6 commences to be reproduced as the scanning point by the lightbeam reverts to the time point P₂₁ temporally previous to the replay endpoint P₁₂ of the first recording layer 4 up to the point P₂₂ of the sametiming as the replay end point P₁₂ of the first recording layer 4. Thelight beam focussing position then is shifted to the first recordinglayer 4 to initiate the reproduction of the first recording layer 4 asfrom the point P₁₂ of the first recording layer 4. The reproduction asfrom the point P₁₂ of the first recording layer 4 continues to a pointP₁₃ temporally posterior to the replay end point P₂₂ of the secondrecording layer 6. When reproduction is to be shifted to the secondrecording layer 6, the light beam scanning position is caused to revertto the replay end point P₂₂ on the second recording layer 6 to reproducethe second recording layer 6 up to the point P₂₃ of the same timing asthe replay end point P₁₃ of the first recording layer 4.

[0077] The signal read out from the first and second recording layers 4,6 in the reproduction timing shown in FIG. 6B is routed to the signalreadout unit 32 so that the replay signal processing is carried out inaccordance with the above-mentioned timing as described above.

[0078]FIG. 6C shows the changeover timing of a five-layered opticaldisc, having five recording layers, as a recording medium, as anotherembodiment of an optical disc having plural recording layers.Specifically, FIG. 6C shows the changeover timing in sequentiallyswitching from one recording layer to another, using a sole opticalpickup, in reproducing the audio data recorded in each recording layerof the optical disc.

[0079] In switching the focussing position of the replay light beam,radiated from the optical pickup, from the first recording layer to thesecond recording layer, from the second recording layer to the thirdrecording layer, from the third recording layer to the fourth recordinglayer and from the fourth recording layer to the fifth recording layer,reproduction reverts to points temporally previous to the replay endtime points P₁₂, P₂₂, P₃₂ and P₄₂ of the previously reproduced layer,respectively. As for the replay timing of the second, third and fourthrecording layers, these layers are reproduced up to the points P₂₂, P₃₂and P₄₂ of the same timing as the replay end points p₁₂, P₂₂, P₃₂ of thetemporally previous recording layer. However, the replay timing of thefifth recording layer is such that the fifth recording layer isreproduced up to a replay end time point P₅₂ which is temporallyposterior to the replay end time point P₄₂ of the fourth recordinglayer.

[0080] In the reproduction apparatus 30, shown in FIG. 5, it is possibleto realize variegated reproduction, such as reproduction of datasynthesized from data of a lyric and data of the accompaniment music forthe lyric, making up with the lyric the complete musical number recordedon the first or second recording layers 4, 6 of the optical disc 1, orreproduction of data corresponding to the entire musical number recordedon one of the first and second recording layers 4, 6 less data of thelyric or the accompaniment music of the lyric of the musical numberrecorded on the other recording layer. In the first and second recordinglayers 4, 6, data of the lyric and data of the accompaniment music of acomplete musical number are recorded, so that audible musical numberreproduction is possible irrespective of on which recording layer theaudio data reproduced have been recorded.

[0081] An embodiment of the recording apparatus for recording audiosignals on the first or second recording layers 4, 6 of the optical disc1 at a pre-stage to the sampling stage by an LPF is hereinafterexplained.

[0082] Referring to FIG. 7, the recording apparatus 45 includes a firstinput terminal 46, fed with audio signals recorded on the firstrecording layer 4 of the optical disc 1, and a second input terminal146, fed with the audio signals recorded on the second recording layer6.

[0083] It is noted that the first input terminal 46 is fed from a soundsource, not shown, with entire audio signals of a complete musicalnumber comprised of a lyric and the accompaniment music for the lyric,as partial audio data, and, the second input terminal 146 is fed with asound source, not shown, with audio signals of an accompaniment musicportion of the complete musical number containing the lyric portion andthe accompaniment music of the lyric portion.

[0084] Alternatively, the first input terminal 46 may be fed from asound source, not shown, with entire audio signals of a complete musicalnumber comprised of a lyric and the accompaniment music for the lyric,as partial audio data, and a second input terminal 146 is fed with asound source, not shown, with audio signals of lyric portion of thecomplete musical number containing the lyric portion and theaccompaniment music of the lyric portion.

[0085] Still alternatively, the first input terminal 46 may be fed froma sound source, not shown, with audio signals of an accompaniment musicfor a lyric of a complete musical number comprised of the lyric and theaccompaniment music for the lyric, as partial audio data, and the secondinput terminal 146 may be fed with audio signals of lyric portion of thecomplete musical number containing the lyric portion and theaccompaniment music of the lyric portion, as partial audio data.

[0086] It is noted that the audio signals fed to the first and secondinput terminals 46, 146 are stereo audio signals of two channels, namelyleft and right channels, enabling the stereophonic reproduction.

[0087] The audio signals, fed to the first and second input terminals46, 146, are processed with sampling with the sampling frequency of 44.1kHz and 16-bit quantization, for each of the left and right channels,for recording on the first and second recording layers 4, 6.

[0088] The first audio signals, input to the first input terminal 46,are amplified by a first line amplifier 47, and then supplied to a firstadder 49 adapted for adding dithering to the signals. The dithering is arandom noise of small amplitude supplied from a dither generator 48.From the first audio signal, added to with the dithering by the firstadder 49, signal components of a frequency range not higher than 20 kHzare taken out by a first low-pass filter (LPF) 50 and thence routed to afirst sampling circuit 51. This first sampling circuit 51 appliessampling at a sampling frequency of 44.1 kHz to a filtered output of thefirst LPF 50. This sampling data is converted into 16-bit digitalsignals by a first A/D converter 52.

[0089] The second audio signals, input to the second input terminal 146,are amplified by a second line amplifier 147, and thence supplied to asecond adder 149 adapted for adding dithering to the signals. Thedithering is a random noise of small amplitude supplied from the dithergenerator 48. From the second audio signal, added to with the ditheringby the second adder 149, signal components of a frequency range nothigher than 20 kHz are taken out by a second low-pass filter (LPF) 50and thence routed to a second sampling circuit 151. This second samplingcircuit 151 applies-sampling at a sampling frequency of 44.1 kHz to afiltered output of the second LPF 150. This sampling data is convertedinto 16-bit digital signals by a second A/D converter 152.

[0090] The first digital audio signals, derived from the first audiosignals output from the first A/D converter 52, are stored in a firstbuffer memory 53. The first digital audio signals, read out from thefirst buffer memory 53, are routed to a first error correction codingcircuit 54 so as to be processed with cross interleaving employing theCIRC algorithm combined with four-order Reed Solomon code. The encodeddata output from the first error correction coding circuit 54 isEFM-modulated by a first modulation circuit 55 so as to be processed forrecording on a first recording circuit 56 and so as to be recorded onthe first recording layer 4 of the optical disc 1 by one of two opticalpickups shown in FIG. 2.

[0091] On the other hand, the second digital audio signals, derived fromthe second audio signals, output from a second A/D converter 152, arestored in a second buffer memory 153. The second digital audio signals,read out from the second buffer memory 153, are routed to a second errorcorrection coding circuit 154 so as to be encoded by the crossinterleaving employing the CIRC algorithm combined with four-order ReedSolomon code. The encoded data output from the second error correctioncoding circuit 154 is EFM-modulated by a second modulation circuit 155so as to be processed for recording on a second recording circuit 156and so as to be recorded on the second recording layer 6 of the opticaldisc 1 by the other optical pickup shown in FIG. 2.

[0092] In the optical disc 1 of each of the above-described embodiments,plural recording layers are provided in superposition and the entiremusical number or a portion thereof is recorded in each recording layeras partial audio data. It is however possible to split the major surfaceof an optical disc 60 into two or more plane portions on which to recordthe entire musical number or its partial portion.

[0093] In an inner peripheral portion of the optical disc 60 shown inFIG. 8, there is provided a first recording region 62, on an outerperipheral side of which there is recorded a second recording region 65.

[0094] In the first recording region 62, the entire audio signals of acomplete musical number comprised of the lyric and the accompanimentmusic are recorded as partial audio signals. In the second recordingregion 65, the audio signals of the accompaniment music of the completemusical number comprised of the lyric and the accompaniment music aresimilarly recorded as partial audio signals.

[0095] Alternatively, the audio signals of the accompaniment music of acomplete musical number comprised of the lyric and the accompanimentmusic may be recorded as partial audio signals, and the audio signals ofthe lyric of a complete musical number comprised of the lyric and theaccompaniment music may be recorded as partial audio signals.

[0096] The first and second audio signals, recorded on the first andsecond recording regions 62, 65, are converted into digital audiosignals from sampling data generated on sampling with the samplingfrequency of 44.1 kHz followed by 16-bit quantization, so as to beprocessed with error correction processing and EFM modulation as in theabove-described embodiment for recording in the respective recordingregions 62, 65, as in the embodiment described above.

[0097] Adjacent to the inner rim of the first recording region 62, thereis provided a first management area 61 for supervising the audio datarecorded on the first recording region 62. Adjacent to the inner rimside of the second recording region 65 and to the outer rim side of thefirst recording region, there is provided a second management area 64for supervising the audio data recorded in the second recording region65. In the first management area 61, there are recorded firstdiscrimination data for indicating the presence of the second recordingregion 65 and second discrimination data indicating whether the datarecorded in the first recording region 62 and data recorded in thesecond recording region 65 are to be multiplexed and reproduced.

[0098] The optical disc 60 has a center opening 67. The first managementarea 61, the first recording region 62 and a first read-out areaassociated with these regions 61, 62 form a first session 68, and thesecond management area 64, the second recording region 65 and a secondread-out area associated with these regions 64, 65 form a second session69.

[0099] The audio data recorded on these recording regions 62, 65 arerecorded such as to be reproduced by a routine reproducing apparatus fora compact disc employing a light beam of 780 nm. The accompaniment musicportion or the lyric portion of a complete musical number, comprised ofthe accompaniment music portion and the lyric portion, are recorded as aset, as in the case of the above-described optical disc 1, so that, ifthe audio data recorded in the recording regions 62, 65 are reproducedindependently of each other, the audio data so reproduced can be heardas the music number.

[0100] The recording medium according to the present invention may be anoptical card or a semiconductor memory, in addition to an optical disc.

[0101] Industrial Applicability

[0102] If a recording medium according to the present invention isreproduced, a musical number composed of the lyric and the accompanimentmusic or the orchestra performed by plural sorts of musical instrumentscan be reproduced as a set of audio signals. Moreover, only theaccompaniment music portion of a musical number composed of the lyricand the accompaniment music, or the performance by only certain musicalinstrument(s) of the orchestras, may be reproduced, so that the user isable to selectively hear a desired one of variegated audio reproduction.

1-7. (canceled)
 8. a recording apparatus for recording audio signals ona recording medium, said recoding medium having a plurality of recordingregions, comprising: sampling means for sampling signals separated intoa plurality of partial portions from audio signals from a sound sourceat a predefined sampling frequency, said plurality of partial portionsincluding said audio signals in their entirety; and recording means forrecording digital data obtained from said sampling means in saidplurality of recording regions of said recording medium.
 9. Therecording apparatus according to claim 8, wherein said predefinedsampling frequency is 44.1 kHz.
 10. The recording apparatus according toclaim 8, wherein said audio signals are reproducible by a discreproducing apparatus employing a light beam having a wavelength ofapproximately 780 nm.
 11. The recording apparatus according to claim 8,wherein said recording medium is a disc shaped recording medium havingfirst and second recording layers within which said sampling data isseparated into two said partial portions that are recorded.
 12. Therecording apparatus according to claim 8, wherein said plurality ofpartial portions are independent partial portions.
 13. The recordingapparatus according to claim 8, wherein said plurality of partialportions represent accompaniment music of a lyric.
 14. A recordingmethod for recording audio signals on a recording medium, said recordingmedium having a plurality of recording regions, said method comprisingthe steps of: sampling signals separated into a plurality of partialportions from audio signals from a sound source at a predefined samplingfrequency, said plurality of partial portions including said audiosignals in their entirety; and recording digital data obtained from saidsampling means in said plurality of recording regions of said recordingmedium. 15-36. (canceled)